The circular city is emerging as new concept and form of practice in sustainable urban development. This is a response to the complex and pressing challenges of urbanization, as highlighted in the New Urban Agenda (NUA). The concept of a “circular city” or “circular city-region” derives from the circular economy model applied in the spatial territorial dimension. It can be associated with the concept of a “self-sustainable” regenerative city, as stated in paragraph n.71 of the NUA. This paper aims to develop an extensive form of “screening” of circular economy actions in emerging circular cities, focusing on eight European historic port cities self-defined as “circular”. The analysis is carried out as a review of circular economy actions in the selected cities, and specifically aims to identify the key areas of implementation in which the investments in the circular economy are more oriented, as well as to analyze the spatial implications of the reuse of buildings and sites, proposing a set of criteria and indicators for ex-ante and ex-post evaluations and monitoring of circular cities. Results show that the built environment (including cultural heritage), energy and mobility, waste management, water management, industrial production (including plastics, textiles, and industry 4.0 and circular design), agri-food, and citizens and communities can be adopted as strategic areas of implementation of the circular city model in historic cities, highlighting a lack of indicators in some sectors and identifying a possible framework for “closed” urban metabolism evaluation from a life-cycle perspective, focusing on evaluation criteria and indicators in the (historic) built environment.

After the 2008 crisis, smart sustainable development of port areas/cities should be developed on the basis of specific principles: the synergy principle (between different actors/systems, in particular the socio-cultural and economic system), the creativity principle and the circularization principle. The Historic Urban landscape (HUL) approach becomes the guarantee that the transition toward the smart city development model is based on specific local cultural resources, and not only on technological innovations. In other words, the eco-town/eco-city strategy becomes culture-led. It stimulates places as spatial “loci” for implementing synergies and circularization processes. Without new evaluation tools and a widespread “evaluation culture” the risks in implementing HUL are very high.

As the world continues to urbanize, identifying and implementing new urban development models and strategies is necessary to face sustainable development challenges. To this end, the circular economy model can be implemented in cities in order to operationalize and achieve human sustainable development managing simultaneously, in a systemic perspective, the social inequalities issue and the ecological and economic crisis. Today there are many cities that are defining themselves as a “circular city” but, to date, a clear definition of this does not exist. In the transition towards the circular city, tools (such as evaluation, governance, financial, business tools) play a fundamental role. The aim of this paper is (after an analysis of the concept of the circular city and its implementation, starting from literature, official documents and reports) to identify and analyze tools for implementing the circular city model. In particular, a set of indicators to assess (positive and/or negative) impacts of projects and initiatives of the circular city agenda is identified.

By referring to the European Green Deal, this paper analyzes the “intrinsic value” of cultural heritage by investigating the human-centered adaptive reuse of this heritage. This implies questions such as how to improve the effectiveness of reuse, restoration, and valorization interventions on cultural heritage/landscapes and how to transform a cultural asset into a place, interpreted as a living ecosystem, to be managed as a living organism. The autopoietic characteristic of the eco-bio-systems, specifically focusing on the intrinsic versus instrumental values of cultural heritage ecosystem is discussed in detail. Specifically, the notion of complex social value is introduced to express the above integration. In ecology, the notion of intrinsic value (or “primary value”) relates to the recognition of a value that “pre-exists” any exploitation by human beings. The effectiveness of transforming a heritage asset into a living ecosystem is seen to follow from an integration of these two values. In this context, the paper provides an overview of the different applications of the business model concept in the circular economy, for a better investment decision-making and management in heritage adaptive reuse. Matera case is presented as an example of a cultural heritage ecosystem. To conclude, recommendations toward an integrated approach in managing the adaptive reuse of heritage ecosystem as a living organism are proposed.

Cultural heritage (CH) is considered a key element of cities and regions’ identity anduniqueness, contributing to people's wellbeing and health, as well as jobs creation, environmentalregeneration and place attractiveness. The adaptive reuse of abandoned and underused CH can be asustainable strategy for heritage conservation, stimulating local development processes. However,heritage conservation needs large investments, while the resources available are scarce, and invest-ment projects are subject to high uncertainties. Therefore, a careful assessment of impacts is neededto orient and direct CH adaptive reuse projects towards sustainability. Recent studies approach theadaptive reuse of abandoned buildings and sites as an effective circular economy strategy, potentiallycontributing to climate objectives through environmental regeneration and the reduction of naturalresources consumption. However, evaluation tools to assess the impacts and orient adaptive reuseinterventions in the perspective of circularity are lacking. Through the analysis of 76 literature sourceson CH impacts, this article explores how indicators are currently used in CH research and practice asimpact assessment tools. More than 3500 indicators were retrieved and classified. Finally, this articleproposes a comprehensive evaluation framework to assess the impacts of cultural heritage adaptivereuse in the perspective of the circular economy. The results show that, while some indicators areavailable, many circularity aspects are not considered in the current studies on CH impacts.